Backpack



FIG. 1 is a front perspective view of the backpack comprising the present invention;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a left side thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

Broken lines shown in the drawings illustrate portions of the backpack, and form no part of the claimed design. 

CLAIM We claim the ornamental design for a backpack, as shown and described. 